Devices for detecting radioactive sources (for example, portal monitors for detecting moving radioactive sources) are devices for prevention of smuggling and illegally carrying radioactive material, and they are playing an increasingly important role in fields such as customs, inspection and quarantine, etc. With the popularity and mass use of such devices, higher requirements are taken into consideration for these devices. For example, an urgent problem for such devices is that there are often innocent alarms triggered by naturally occurring radioactive material (such as chemical fertilizers, bananas, ceramics, marble, etc.) during the use of the devices, and these alarms account for a considerable proportion in all the alarm events. In the absence of any action, this would add a lot of work to the staff (especially in ports with a high throughput), and thus greatly reduces the efficiency of custom clearance.
In order to reduce the negative impact of these alarms on operations in the ports, there is proposed a solution of determining the types of radioactive sources (innocent or not) by manually observing the shape of a count rate profile. The solution has been applied to large-scale ports with a lot of devices, and has improved the efficiency of clearance to a certain extent.
However, although the method of manually observing can solve the above problem to a certain extent, in order to implement this solution, in-depth and meticulous training for picture observing staff are required, and the observing staff will have to concentrate all the time during work, which is an unnecessary burden. Taking China Custom as an example, custom officers need to work in a job rotation mechanism, which means that a new round of training will be required after each round of rotation, and the experience that accumulated by the last group of picture observing staff will result in nothing. In addition, the picture observing staff typically have to work for a long shift, which may cause them difficult to maintain concentration throughout the entire shift time. Job positions may be increased so that the work shift for a single person will be reduced, however, this will not ensure a better observing level, and on the other hand, will increases the personnel burden for the administration of the custom.